> Hi Graham!
>
> You would strip the whole board? There are wires already on some of these
> assemblies, that's been tacked down with RTV, and practically every assembly
> has socketed components, along with right angle interconnecting female
> sockets, wouldn't one worry about getting the stripping chemistry trapped
> inside these small areas?
>
> I've heard more than just a few times that whatever chemistry works well in
> stripping urethanes, also poses a risk in affecting the laminate, and part
> marking...something that we can't afford even risking.
>
> That's why I'm looking at spot removal. I've been looking at a CCR Company
> workstation, the same one that Jim Marsico has, and emailed him off-line with
> some questions. He really likes it.
>
> Just wondering if anybody else has a system that they would like to share some
> details about with me, good or bad, off-line if need be.
>
> As always, Thanks in advance!!
>
> -Steve Gregory-
>
>
> Hello friends, busy week so sorry for a late input.
>
> I have only one piece of advice for Steve and others regarding repairs to
> Urethane based coatings it is very difficult to return to a monolithic film
> as Urethane systems tend to laminate.
>
> The repair coating will therefore need to be applied to a far wider area than
> that ³spot² you fixed. It is possible that the lamination² will be a path for
> ingrees of the stuff you are trying to keep out.
>
> It is for this reason that Acrylics are more popular, because they will more
> readily return to monolithic film....and before anyone asks, no, you should
> not repair a urethane with an acrylic. The product has a coating that was
> carefully selected and qualified. Same generic type but different supplier
> MIGHT be OK, but you MUST check this with the originator.
>
> Our route in this situation is to fully strip using a suitable solvent
> stripper bath clean, repair, re-clean and then re-coat. It is easier and it
> looks better.
>
> Hope this helps
Hiya Steve,
Sorry for the delay, but I am preparing for 2 days of committee meetings
with the IEC this week aaaarrggghhh!
Noting the other postings, and establishing these to be military boards but
a nightmare to rework obviously my suggestion/ recommendation for total
stripping will be problematical, but donıt discard it! Do people die if this
product fails? Then maybe you would need to replace many or all of those
tricky little *******!
If you do spot rework, and you will know if this is best by now, then just
please heed my point about lamination, and ensure that you do get rid of all
flux residues when you have done the repair, and then make sure that the
coating is applied over a much wider area than only the immediate point of
repair.
Good luck.
--
Regards Graham Naisbitt
[log in to unmask]
Cell: 079 6858 2121
Office: +44 (0)1252 813706
Concoat Limited - Engineering Reliability in Electronics
Web: www.concoat.co.uk and www.concoatsystems.com
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